Biological Sciences Research Highlights

First Study on the Mitochondrial Outer Membrane Subproteome Appears in Proteomics

Researchers from Pacific Northwest National Laboratory, three German institutions, and Stanford University performed the first study on the subproteome of the mitochondrial outer membrane to discover novel functions of its components. The mitochondrial outer membrane mediates numerous interactions between the metabolic and genetic systems of mitochondria and the rest of the eukaryotic cell.

The researchers analyzed mitochondria from Neurospora crassa (red bread mold), a popular experimental model organism. They identified proteins of N. crassa's outer membrane vesicles (OMV) using a combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) of tryptic peptide digests and gel electrophoresis of solubilized OMV proteins, followed by MALDI-MS peptide mass fingerprinting (PMF). The tryptic peptides were prepared and analyzed at the Environmental and Molecular Sciences Laboratory at PNNL. The work was sponsored by the National Institutes of Health and five German agencies.

The study revealed that the mitochondrial outer membrane contains at least 30 different proteins. Among those are components of the import machinery, a pore-forming component (Porin), and proteins that control fusion and fission of the organelle.

This study is an important step towards determining the complete set of proteins in this membrane. Although the current set is incomplete, it will serve as a framework for future studies on the proteome of the outer membrane from higher eukaryotes such as plants and mammals.

PNNL scientist David Camp was co-author of the study results, which appeared in the January 2006 issue of Proteomics. Other authors were Simone Schmitt, Thomas Waizenegger, Tilman Schlunck, Axel Imhof, Walter Neupert, and Doron Rapaport, Ludwig-Maximillians-Universitat, Munich; Holger Prokisch and Thomas Meitinger, GSF National Research Center and the Technical University of Munich; Uwe Ahting, GSF National Research Center; and Curt Scharfe and Peter Oefner, Stanford Genome Technology Center.